#include <stdint.h>
#include <stdbool.h>

Functions
uint16_t	_MinPeak (uint16_t target, uint16_t target_tolerance)

uint16_t	_MaxPeak (uint16_t target, uint16_t target_tolerance)

Variables
uint8_t	max_tries
	maximum number of tries before AutoExpose() gives up

uint16_t	start_pixel
	AutoExpose() ignores pixels below `start_pixel`.

uint16_t	stop_pixel
	AutoExpose() ignores pixels above `stop_pixel`.

uint16_t	target
	target peak counts for AutoExpose().

uint16_t	target_tolerance
	`target` ± `target_tolerance` is the target peak counts range for AutoExpose().

uint16_t	max_dark
	`max_dark` is a conservative estimate on the largest dark offset

uint16_t	min_exposure
	`min_exposure` is 100 microseconds (five 20µs-cycles) This is a safe lower limit to avoid dead frames.

uint16_t	max_exposure
	`max_exposure` is 1.31 seconds (65535 20µs-cycles) This is the 16-bit limit, UINT16_MAX, but it is also a practical limit on waiting time for one frame. More...

Detailed Description

Global AutoExpose config

AutoExpose maximum number of tries

AutoExpose gives up if it cannot hit the target peak counts range after max_tries attempts. Recommended value is 10. Use smaller numbers to speed up AutoExpose. Set the value to 1 to manually trigger each iteration and get a sense of how many tries are necessary to hit the target range. The range of allowed values is 1 to 255.

AutoExpose pixel range

Recommended values for start_pixel and stop_pixel depend on the spectrometer pixel-to-wavelength map file:

start_pixel: smallest pixel number in the map file
stop_pixel: largest pixel number

The default pixel range on power-up is:

start_pixel = 7
stop_pixel = 392

With binning on, the default pixel range is also the allowed range of values. Attempting to exceed this range, it is clamped at these boundaries. With binning off, the allowed range is start_pixel = 14, stop_pixel = 784.

AutoExpose target peak counts range

Recommended values for target and target_tolerance are:

target: 46420 counts
target_tolerance: 3277 counts

See details in the Doxygen for AutoExpose(). Allowed values for target are in the range 4500 counts to 65535 counts. Attempting to set a target less than 4500 counts, target is clamped at 4500 counts. If the combination of target and target_tolerance results in target ranges extending below 4500 counts or above 65535 counts, the target tolerance is ignored and the target range is clamped at these boundaries.

Definition in file AutoExpose.h.

Variable Documentation

◆ max_exposure

uint16_t max_exposure

extern

max_exposure is 1.31 seconds (65535 20µs-cycles)
This is the 16-bit limit, UINT16_MAX, but it is also a practical limit on waiting time for one frame.

For longer exposure times:

change the datatype in firmware to uint32_t
revise all transmissions of exposure_ticks in VisCmd.h and UsbCmd.h to send/receive four bytes
update the Python API by changing all occurrences of cycles in the JSON file from size:2 to size:4.

Definition at line 12 of file AutoExpose.c.

Functions